Effect of the different YopD mutations on pore formation.

<p><b>A.</b> HeLa cells were left uninfected or infected with <i>yopEHJD</i>, <i>yopEHJD</i>/pYopD and <i>yopEHJD</i> expressing the different <i>yopD</i> mutants at MOI of 100. After 3 h infection, culture supernatants were removed and tested for LDH release. Background LDH released from uninfected cells was subtracted from infected wells. Results were normalized to <i>yopEHJD</i>/pYopD (100%). Error bars represent the standard deviation of the mean values obtained from four duplicate experiments. ** P<0.0001, * P<0.0005 determined by t-test. <b>B.</b> HeLa cells on coverslips were infected as described above for the LDH assay, and stained with DEAD-LIVE kit as described in Material and Methods. Cells with disrupted membranes exhibit a red nuclei staining.